The invention relates to a filter device for filtering a liquid, in particular a hydraulic oil, having a substantially cylindrical filter housing, which accommodates a filter element and can be closed off by means of a cover, the filter element having an associated untreated region with an inlet for supplying liquid which is to be filtered and a clean region with an outlet for removing filtered liquid, and the filter element comprising an end plate which is remote from the cover and on which there is mounted a radially acting sealing element for sealing the untreated region of the filter element.
Filter devices of this type are used, for example, to filter mineral oils in hydraulic systems. In this case, the hydraulic systems have to satisfy very high demands with regard to the hydraulic oil being clean, so that they can fulfill their function without faults and with little wear over prolonged operating times. Since the filter element gradually becomes blocked with dirt particles during the operating time, it is usually mounted exchangeably in the filter housing. The sealing element mounted on the end plate ensures that the unfiltered hydraulic oil fed to the untreated region cannot bypass the filter element inside the filter housing, but rather the untreated region is reliably sealed. O-ring seals which are held against the end plate are customarily used for this purpose. For this purpose, the end plate usually comprises an O-ring groove for accommodating the O-ring.
In DE 197 18 603 A1, it is proposed for a sealing lip, which is pressed onto a corresponding sealing surface by means of a clamping ring, to be formed onto the end plate of the filter element. The clamping ring exerts a compressive load on the sealing lip, so that the sealing action which is required for the filter device to operate is ensured. In addition to the use of the clamping ring, it is in this case proposed for the sealing lip to have two sections which are oriented obliquely with respect to one another and in their transition region form a sealing edge for bearing against a sealing surface. Therefore, the sealing element has a configuration of complex construction, and when the filter element is being exchanged, careful attention must be paid to ensuring that the clamping ring exerts on the sealing lip the compressive force which is required in order to produce a seal.
It is an object of the present invention to develop a filter device of the generic type in such a manner that it can be produced at lower cost and the filter element can be assembled more easily.